This invention relates to a microprocessor configuration for control systems for vehicles that, for example, comprise inter alia anti-lock control systems (ABS), traction slip control systems (German abbreviation ASR=TCS), systems for electronic control of the braking force distribution (German abbreviation: EBV=EBD) as well as for yaw torque control, and driving stability control systems (German abbreviation: GMR=YTC; FSR=DSC; and ASMS), etc.
A great number of such control systems and system variants is known. Nowadays, the importance of such systems is rapidly increasing in view of the demand for higher safety standards and for more comfort.
It is also known to combine a plurality of control systems to form a compound system as the various functions are interactive and as parts of different control systems such as sensors, circuits for detecting and processing input control signals, monitoring systems etc. can be used jointly.
Microcomputer structures of various types are used for solving complex arithmetical problems. From DE 32 34 637 C2, e.g., an anti-lock control system has come to knowledge the control unit of which includes two or more parallel-working microcontrollers for the generation of braking pressure control signals. These microcontrollers process the same input signals in accordance with an identical computer program. The output signals and internal signals of the microcontroller are monitored for concurrence in order to detect any malfunctions in either of the two controllers. Electronic control will be switched off if the signals redundantly processed in the microcontrollers are differing from each other. This is done in order to ensure that the braking function, even if uncontrolled, will be kept up also if there comes up an error in the electronic system.
Such a circuit configuration with so-called asymmetrical redundancy also has already come to knowledge from DE 41 37 124 A1. In this circuit configuration, the input signals of the control system, namely the signals obtained by means of wheel sensors and representing the rotational behavior, are fed to two parallel microcontrollers. Only one of these two microcontrollers works through the full control program while the second microcontroller simulates the input information in a simplified form, processing it in accordance with simplified algorithms. By comparing the data processing results of the two microcontrollers for concurrence or, at least, for plausibility it is possible to recognize malfunctions or defects in the electronic system despite the simplified data processing.
Further, a microprocessor configuration of the type mentioned above is known from DE 44 39 060 A1(P 7714), which includes a plurality of microprocessor systems interconnected by bus systems. By means of this configuration it is possible to carry out anti-lock control and traction slip control as well as, at least, one further control function requiring complex computing operations, the monitoring functions included. This known microprocessor configuration includes three microprocessor systems, with the individual functions being allocated to these microprocessor systems so that the first microprocessor system, together with the second microprocessor system, takes over the ABS and ASR (=TCS) functions, the monitoring of these functions included. The third microprocessor system, together with the second microprocessor system, carries out the further control function (GMR=YTC), which requires complex computing operations, and the monitoring thereof. For the purpose of monitoring, this configuration makes use of the asymmetrically redundant data processing (by means of different computing processes or computer systems) or of the symmetrically redundant data processing (by means of like computing processes or computer systems) in two microprocessor systems at a time.
A high-degree operational reliability is achieved by means of the installation, described in the aforementioned DE 44 39 060 A1, of the various functions in only three microprocessor systems, the redundant signal processing included which serves monitoring purposes. If certain malfunctions of one control component are detected it will moreover be possible to switch off this component, only, while continuing other control functions.
It is now an object of the present invention to develop a microprocessor configuration for a complex vehicle control system, comprising a plurality of control components, which enables an even better, more sensitive and more balanced allocation of the monitoring of individual control functions or control systems with regard to safety demands or rather to the importance of these functions for the safety of the vehicle. What should be achieved in a way is the realization of a balanced safety concept.